Peavey DECA-1200
A 26-pound rack amp that Peavey claimed runs at 90 percent efficiency - and the touring crews who ran them on heavy metal shows measured a couple of amps at the wall, not fifteen.
Overview
The number that sold this amplifier was never the wattage. It was the efficiency claim. Peavey built the DECA-1200 around what the company called Digital Energy Conversion Amplification, a design it described in its own advertising as "the world's first (and only) 90 percent efficient and truly digital power amplifiers." That copy ran in Mix-Magazine (July 1985, p.31) and again in Sound-and-Communication (March 1985, p.34). Peavey's own pitch drew the contrast: conventional linear amplification manages somewhere between 40 and 60 percent efficiency, so hitting 90 percent meant leaving Class AB entirely. The company insisted the DECA was not a conventional Class AB amp "passed off under some fancy name," and that its technology was not analog. Peavey applied for six patents on the approach. Whether "digital" is the right word for a switching topology is debatable, but the efficiency claim is the reason this amp exists.
The output ratings explain the model number. Peavey rated it at a minimum of 600 watts RMS into 4 ohms per channel, and 1200 watts RMS into 8 ohms in bridge mode. The smaller DECA-700 in the same series was rated at 350 watts RMS per channel into 4 ohms and 700 watts into 8 ohms bridged, so the naming follows the bridged figure, not the per-channel one. Both amps are 19-inch rack mount units that take up two spaces.
The weight is what surprises people who have only read the spec sheet. Peavey listed the DECA-700 and DECA-1200 at 24 and 26 pounds respectively. For a two-space rack amp rated at 600 watts per channel into 4 ohms, that is very little mass, and the company put it down to the efficiency of the design. Less waste heat means less heatsink, and less heatsink means less iron in the chassis. The advertising leaned on this hard, promising the amps "deliver time after time with virtually no heat."
The best corroboration of the efficiency claim does not come from Peavey. Vista, a sound company running a modular loudspeaker system built around McCauley components and TAD 4001 compression drivers, chose DECA-1200s to power their rig. That is a working sound company reporting a real-world measurement well under the manufacturer's own worst-case figure, which counts for more than any spec sheet line.
Peavey's feature list for the series included DDT compression circuitry to prevent amplifier overload, and the company claimed no measurable TIM or slew rate induced distortion. Multiple overload, output, and load protection features were standard. Later Peavey literature describes the series as combining MOSFET designs with high-speed digital computer electronics and electromagnetic energy conversion technology. It also refers to a "digital version" of the company's patented DDT compression circuit that virtually eliminates the possibility of driving the amplifier into distortion. The DECA series won Music & Sound Output and Music & Sound Retailer "Most Innovative Product" awards in the Sound Reinforcement category in two consecutive years. Peavey's own materials describe the DECA 724 and DECA 1200 as the most popular new amps among sound professionals for 1986 and 1987. That last claim is manufacturer copy, not an independent tally.
From the available documentation, the DECA-1200 is not a hi-fi amplifier. Every period mention places it in sound reinforcement: powering a touring PA, driving modular loudspeaker enclosures, racked two spaces high in a road case.
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